Method of producing drill bits



Och 14, 1947. M. G. WRIGHT 2,428,823

METHOD OF PRODUCINGIIDRILL BITS Filed ma 18, 1943 5 Shets-Sheet 1 Mucus G- Wmcnr INVENTOR.

ofan 719W ATTORNEK Oct. 14, 1947. M. G. w em 2,428,823-

METHOD OF PRODUCING imILL BITS Filed May 18', 194:5 s Sheets-Shae; 2

+ 4 FIG-"5- Mmcus G. Wwcnr INVENTOR A TTORNEK 3 Sheets-Sheet 3 Oct. 14, 1947. M. G. WRIGHT METHOD OF PRODUCING DRILL B'ITS FiIedMay 18; 1943 :25: U 1 2:51 i l; i I

ATTORNEK Patented 0011.14, 1947 METHOD OF PRODUCING DRILL BITS Marcus G. Wright, Denver, 0010., assignor of thirty-five one-hundredths to Thomas P. Campbell and thirty-five one-hundredths to W. Myron Owen, both of Denver, Colo.

Application May 18, 1943, Serial No. 487,437

This invention relates to drill bits for core drilling and the like, and specifically to a method of producing such bits. More particularly, the present invention relates to drill bits of the type shown and described in my co-pending application Serial No. 460,828 and certain features described but not claimed herein have been made the subject matter of claims in the aforesaid application.

Drilling apparatus of the aforesaid character is used in many different types of operations, and the structures drilled frequently possess a high degree of hardness and usually are quite abrasive. Consequently, such drilling is likely tobe a powerconsuming and tedious operation, causing rapid deterioration of the drill bits.

In an effort to reduce excessive wear on drill bits, the industry has utilized diamonds, carboloy and similar compositions possessing an extreme degree of hardness, as constituents of the drill bits. However, the problem of embedding such compositions in the drill bit structure has not been easil solved, and the methods heretofore in use either have involved too much production expense in providing a satisfactory product, or have been only partially satisfactory for their intended purpose.

It is an object of the present invention to provide a simple, efficient and economical method of producing durable drill bits possessing eflicient drilling properties.

Another object of the invention is to provide simplified methods for producing drill bits that are suited for use with a variety of materials.

A further object of the invention is to provide a method for producing a simple, durable and efiicient drill bit.

Other objects reside in novel steps and treatments and novel combinations and arrangements of steps, all of which will be explained in the course of the following description.

Briefly stated, the novel method of the present invention involves forcefuly depositing a mixture of molten metal and an abrasive, such as diamond chips, on the end of a piece of tubular metallic stock, and forming said metal-abrasive intermixture after deposit on the stock into an annular cutting surface, having a series'of passages for removal of a core and circulation of a heat-exchange fluid about the bit.

The aforesaid method may be performed in a variety of ways, and utilizing different appara-' tus and in the accompanying drawings typical operations utilizing features of the invention have been illustrated. In the drawings in the several views of which like parts have been designated similarly, l

8 Claims. (01. 76-108) relation to turntable l2.

Figure 1 is a fragmentary side elevation, partially in section, of the arrangement of apparatus used in forming drill bits according to the present invention in a metal spraying action;

Figure 2 is a top plan view of the turntable utilized for the support of drill bits and stock in performing the operation illustrated in Figure 1;

Figure 3 is a side elevation of one of the drill bits produced by any of the several methods disclosed herein;

Figure 4 is an end view looking toward the crown of the drill bit illustrated in Figure 3;

Figure 4a is a section througha drill bit of the type shown in Figures 3 and 4 at an incomplete stage in its formation and corresponding to the location shown by the lines 4A-4A of Figure 3;

Figure 5 is a side elevation, partially in section, of a press assembly for forming drill bits according to the present invention;

Figure 6 is a fragmentary side elevation of the press assembly of Figure 5 showing another stage in the operation of forming drill bits according to the present invention; and

Figure 7 is another fragmentary side elevation of the press assembly of Figure 5 showing a stage in a different operation of forming drill bits.

Referring first to Figures 1 and 2, a metal spray operation for forming drill bits is illustrated. In this operation, a piece of tubular stock 8 is first threaded at one end as indicated at 9, and provided with soft lead, channeled inserts 40a: (see Figure 4A) at its opposite end, and is then mounted on a spindle Ill journaled on a turntable 12. A cap element [3 supported on a stem I4 which fits into the hollow portion of stock 8 is held in spaced relation from the upper end of stock 8 by inserts 40a: and determines the-thickness of the crown portion that can be formed on the stock.

A shield I5 is mounted on the periphery of turntable l2 and extends to an elevation slightly below the upper end of stock 8 and in close proximity to the periphery of the stock as it spins on the spindle. This shield determines the inner limit of the crown formed on stock 8 by the spraying operation.

A plurality of spindles I lLhere shown as four, but which may be any number permitted by the size of turntable II, are mounted on the turntable and rotated by a drive shaft"; through the intermediary of belts I'l. The turntable is mounted for rotation on another shaft l8, the rotation of which is automatically controlled in a manner that will be described subsequently.

A metal spray gun, designated generally by the reference numeral 19 is mounted on a standard 20 or other suitable support and held in fixed Various guns of this temperature flames, and sprayed by a compressed air blast in fine molten particles against any surface toward and in proximity to which the nozzle 22 is pointed.

The hightemperature flame is produced by a mixture of oxygen and some other gas such as acetylene, propane or the like. To this end, a battery of conduits, 23, 24 and 25, deliver the gases to the gun l9 from a suitable source of supply. The conduit 23 is connected with a suit-. able compressor (not shown) for supplying the compressed air for the discharge blast. The compressed air also is used to operate a turbine in the gun which provides the power for feeding the wire through the gun at constant speed.

Conduit 24 communicates with a suitable oxygen supply source, and conduit 25 communicates with a suitable acetylene supply source. These gases are held at predetermined pressures by regulators. As the details of such systems are well known in the art, the supply sources and regulators have not been illustrated in the drawings.

The wire 26 is fed into the rear end of gun i9 from a suitable supply source (not shown) and is then melted in the action hereinbefore de scrlbed in the nozzle 22. This nozzle has a central passage 27 which narrows in width from the inner end to the outer end of the nozzle and the Wire 26 is fed through this passage until melted in a combustion chamber 28 adjoining its discharge outlet 29.

An annular passage 38 in spaced but proximate relation to passage 21 delivers the oxyacetylene gas to combustion chamber 28, while an outer annular passage 3| delivers the compressed air blast to chamber 28. Abrasives, such as diamond chips, are fed at a controlled rate from hopper ates the turntable mechanism to rotate shaft It a partial turn, to bring a new spindle into register with gun I3. r

In this case the rotation is through an arc of 90, at which point the movement is automatically stopped, the circuit is opened and the turntable rotation arrested until the switch again is actuated by the contact of crown 36 with bar 33.

Between each actuation, or at least before the turntable has made a complete revolution, the machine operator withdraws the crowned bit stock and inserts new pieces of stock in place of each one so removed.

The metal spraying action, although employing temperatures high enough to melt the metal wire,

does not transmit an appreciable amount of heat to the base metal oi. the stock and consequently warping, crystallization, heat strain and the like are'avoided. Upon reaching the surface of the stock, the particles of sprayed metal chill'almost instantly while the abrasive particles are embedded by the hardening action. In this way, a

. strong and tenacious bond is attained.

, When it is necessary to stop the operation, the

gun can be stopped by actuation of a control switch 38 and a gas regulator valve 39. Excess metal and abrasive depositing on the turntable l2 after striking shield 32 are collected periodically I and may be utilized in the manufactureof drill bits by other methods hereinafter described, or may be used in forming other abrasive'articles.

Following removal from the turntable the crowned stock is heated to melt inserts 48x, and removing them together with adhering matter forms a plurality of slots 39-onthe cutting face of the crown portion 36. These slots 39, preferably four in number at 90, intervalsas shown in V 9 Figure 4, form 'continuations of inner and outer s to the present invention involves an initialmixe 2| to chamber 28, and the discharge through outlet 29 comprises an intermixture of molten metal and abrasive particles in an air stream traveling at high velocity.

This mixture deposits on the exposed surface of stock 8 between cap i3 and shield 15 and due and is substantially U-shaped to provide an enclosure for the spindle l0 and associated stock 8 which is positioned to receive the metal spray. This shield has a slot 33 along each side of the U in the path of the spindles I0 as they are rotated by-shaft l8. I

This rotation is periodic or intermittent and is determined by a switch 34 having a contact bar 35, the outer end of which is disposed at the elevation of the space between cap l3 andstock T 8; and at a distance from the stock which is equal to the predetermined thickness of a crown 36 passages 40 and 40a respectively, extendingv lengthwise of stock 8, 7

Following this forming operation, the drill bits are in condition for use and may be and. preferably are used in association with apparatus of the type shown and described in my aforesaid pending application.

Another method of forming drill bits'according ture of metal and abrasive, which is subjected to a high compression in a suitable mold thereby bonding the crown on the metal and shaping it in: a single operation. The abrasive-metal intermixture preferably employs metal shreddlngs and abrasive particles mixed in a ball mill or the like,

although a mixture of metal foil and abrasive may be substituted, if desired. Preferably, at least a portion of the metal comprises the collecgedde posit from turntable ll of Figure 1. r

A press and mold arrangement suitable for performing the aforesaid operations has been 11- lustrated in Figures 5, 6 and 7. The press for performing this operation may be of any convenbeing formed thereon. When the crown is built I up sufliciently to engage switch bar 35, the switch closesa circuit through conductors 31 which actu tional form and is designated generally by the reference numeral 4|. The base 4Ia of the press 4| has a plurality of threaded bores 42 for the reception of nuts 43 clamping a mold member 44 on said base.

Another series-of passage 45 extend through base lla and receive guide rods 46 of an electing device 41, the function of which will be described subsequently. A plunger 48 is Joumaled in press 4| for movement toward and away from mold 44' and has a suitable socket (not shown) for attachment of die members 49 adapted to engage work in mold 44 when the plunger is moved to the limit A ofits downstroke position. I

The mold 44 has a cylindrical bore 50 extending entirely through it from top to bottom and in the upper portion of the mold the bore widens as indicated at 50a and terminates in a tapered entrance 5|. The bore 50 is designed to provide a close clearance for the tubular-stock 8, and a piece of said stock is inserted into this bore'with its threaded end 9 engaging base member 4ia. When so positioned in the mold bore 50, the upper end of stock 8 extends into the widened bore portion 59a a distance slightly less than the P etermined width of the crown portion 36 to be formed on stock 8, as will bebest understood by reference to Figures 6 and '7.

An insert member consisting of a cylindrical shank 52' and a conical head 53 is fitted in the hollow interior of stock 8 and extends above the upper end of the stock for a. substantial distance to provide an annular compression zone within bore portion 50a. The diameter of the shank 52 and the wider end of conical head 53 provides a slight clearance with the inner wall of die member 49.

The die member 49 is of a length calculated to penetrate substantially the entire length of bore portion 59a when the plunger 48 is moved to its extreme downstroke position, and as a consequence exerts a compacting influence on material deposited in the compression zone encompassing the upper end of stock 8.

Thus, if metal foil and abrasive are premixed as by grinding in a ball mill or the like to form an intimate intermixture and a quantity of said intermixture is deposited in the compression zone as indicated in Figure 6, actuation of the press mechanism to force the die member 49 to its extreme downward position through conjoint movement with plunger 48, will serve to compact the intermixture into a metallic mass in which the abrasive is well distributed and firmly bonded.

As the insert member 52, 53 prevents escape of any of the intermixture into the hollow interiors of stock 8 or die 49, the compactin action serves to bond the metallic mass on the end of stock 8 and forms the crown 36 as an integral part thereof. The plunger is nextraised away from the mold, withdrawing die member 49 from bore 50, whereupon mechanism can be actuated to elevate ejector 41 into abutting relation with base 41a thereby elevating stock 8 to a position in which it can be removed from mold 44.

Figure 7 illustrates another operation in Which the arrangement of parts and functioning of the apparatus is duplicated, but in which the compressible intermixture is metal shreddings and abrasive. The compacting action serves to bond the abrasive to the resulting metallic mass and said mass likewise is firmly bonded on the stock 8. Other intermixtures such as the collected deposit from turntable 12 of Figure 1 may be treated .silmilarly with equivalent results.

In such actions, the die member 49 preferably is shaped to form the slots 39 and grooves 49 and 40a in the same action in which the crown 36 is formed. From the foregoing it will be apparent that drill bits of uniform dimension and quality within reasonable tolerance limits are formed by employing any of the aforesaid methods,

It will be apparent that the operations just described may include a battery of molds and dies associated with a single actuating mechanism, and if desired, the feeding and discharge actions may be completely automatic, or may be a com bination of manual and mechanical actions. With all such arrangements, the time required in and 2. One variation involves the omission of the.

inserts 40:: from the stock and the substitution of an indexed drive of spindles ill for the constant speed rotation illustrated. With such an arrangement the spindles ID are rotated at relatively slow speed throughout substantially of a revolution, for example at the rate of about 6 I revolutions per minute.

Then for the few degrees of a revolution representing the width of slots 39 the rotation is in-.

creased to a rate of about 200 revolutions per minute, after which the 6 revolution rate is resumed. This action is repeated through each 90 of revolution or whatever other spacing interval between slots 39 is desired. Due to the high rate of travel at the 90 divisions, an inconsequential deposit of spray metal is obtained and this is readily removed at the completion of the operation to complete the formation of slots 39, if desired.

In either of the metal spray operations hereinbefore described, it may be desirable to direct the spray at the end of stock 8 rather than at the side of same. This can be done by setting the gun l9 to discharge downwardly onto the turntable l2, in which event forced feeding .of abrasive would have to be substituted for the gravity feed from hopper 2|.

Another and perhaps more convenient ar rangement can be effected by mounting turntable I! on a horizontal rather than a vertical shaft as depicted in Figure 1. In all such modified operations the cap element it will be reduced in diameter to correspond to the inner diameter of stock 8 and the height of the crown 36 will be determined solely by the spraying inte val employed.

The various metal spray operations her'einbefore described are particularly effective in producing crowns on drill bits of a novel character. Heretofore, the metal in which the abrasive is embedded has been relatively soft as compared with the abrasive. are operated the abrasive-gripping surfaces of the metal deform and loosen their hold on the abrasive, which drops out and is lost long before the wear on its surfaces has rendered it unfit for further useful work.

Due to the relatively hard binding surfaces provided by the metal spray operation, the abrasive in the bits of the present invention does not become loosened as above described and is retained in the crown throughout substantially its entire useful life.

The several methods hereinbefore described are not intended to be limited to the operations of the apparatus shown and described, but may be performed in a variety of apparatus capable of performing the functions hereinbefore described. For this reason. the representations of apparatus shown in the drawings are intended to bemore or less diagrammatic and are incomplete in the sense that only such parts as are necessary in performing the necessary steps and treatments have been illustrated.

Again referring to the metal spraying operations of the present invention, a variety of metals may be used in the metal spray which have not been used in abrasive bits in the past. For ex- Consequently, when the bits,

ample, high carbon steel, nickel alloy steel and other hard, high tensile metals may be used. similarly, when the inserts 40.1; are used, various metals having a low melting point may be utilized Y in forming the inserts.

As an example, lead, tin, or alloys having similarproperties will be found satisfactory for this purpose.

In all the spraying operations hereinbefore de scribed, it will be desirable to initially roughen the'surfaceof the stock at the end on which the crown is formed to get a better bonding action. Likewise in the press'methods described herein,

the crown end of the stock may be slotted or introducedinto the mold in stratified arrange-' ment, and by proper proportioning of ingredients, the abrasive will be substantially uniformly dis tributed throughout the crown so formed. Such a method may be usecl'when the metallic composition is metallic shreddings, metal gauze or metal foil. Likewise, when desired the intermixture may be subjected to heating in conjunction with the compression'to more firmlybond the crown on the tubular stock.

Persons skilled in the art of manufacturing drill bits will be able to adapt operable arrangements for the metal spraying operation or the compressing treatments by following the procedure described herein and illustrated in the 8 .the rotating stock with a mixture comprising molten metal and abrasive particles, cooling the mass during deposit on the stock, continuing the spraying operation until a measured amount of the cooled mass'has been deposited on the stock,

and spacing the deposit ofmatter on the stock 1 to form a plurality of slots at uniform intervals in the face of the deposited matter.

5. The method'of producing drill bits, which comprises mixing a molten metallic composition in divided condition with abrasive particles in flne sizes in' a spraying action, forcefully depositing said intermixture on a piece of tubular stock in the spraying action to form a crown thereon, forming a plurality of slots at uniform intervals in the face of the crown, and forming means on the stock adapted for attaching the bit so formed to a drill.

6. The method ofproducing drill bits, which comprises threading one end of a piece oft'ubular metallic stock, roughing the surface of the stock at its end remote from. thethreaded por-v tion, rotating said stock, spraying the roughened surface of said rotating stock with a mixture comdrawings. Changes and modifications may be availed of within the spirit and scope of the invention as defined in the hereunto appended,

claims.

What I claim and desire to secure by Letters 1 metal and abrasive particles, shielding the bore of the stock from deposit of matter therein during said spraying action, cooling the mass during deposit on the stock, and continuing the spraying operation until a measured amount ofthe cooled mass has been deposited on the stock. 3.- The method of producing drill bits, which,

comprises threading one end of a piece of tubular metallic stock, mounting low melting-point metal inserts at the periphery of the stock, rotating said stock, spraying the rotating-stock adjacent said inserts with a mixture comprising molten metal and abrasive particles, cooling the mass during deposit. on the stock, continuing the spraying operation until a measured amount of the cooled mass has been deposited on the stock, and form-I ing a plurality of slots in the face of the deposited matter at the completion of the spraying treatment by melting the inserts.

prising molten metal and abrasive particles, cooling the mass during deposit on the stock, and continuing the spraying operation until a measured amount of the cooled mass has been deposited on the stock.

-'7.'The method of producing drill bits, which comprises threading one end of a piece of tubular metallic stock, roughing the surface of the stock at its end remote from the threaded portion, ro-

tating said stock, spraying the roughened surface of said rotating stock at spaced intervals with a Y mixture comprising molten metal and abrasive particles, cooling the mass during deposit on the stock, and continuing thespraying operation until a measured amount of the cooled mass has 4. The method of producing drill bits, which."

comprises threading one end of a piece'of tubular metallic stock, rotating said stock, spraying been deposited on the stock.

-8. The method of producing drill bits, which comprises mixing a molten metallic composition in divided condition with abrasive particles in.

I fine sizes in'a spraying action rotating a piece of 45 stock adapted to form atleast a portion of a drill bit; forcefully depositing said intermixture on said rotating stock in the spraying action to form a crown thereon; and shielding said stock to limit the deposition of.said intermixture to a piedetermined portion of said tubular stock.

, MARCUS G. WRIGHT.

REFERENCES CITED The following references file of this patent:

Number Name Date 1,625,463 Gauthier Apr, 19, 1927 2,147,843 vJamar et a1. Feb. 21, 1939 2,014,955 Taylor Sept. 17, 1935 2,299,207 Bevillard Oct. '20, 1942 2,137,201 Boyer Nov. 15, 1938 2,137,329 Boyer Nov. 22, 1938 2,173,833 Fitz-Randolph Sept, 26, 1939 2,270,209 Van der Pyl Jan. 13, 1942 2,145,888 Moulton et al Feb. 7, 1939 1,848,182 Koebel Mar. 8,1932 2,317,173 Bleakley Apr. 20, 1943 2,233,304 Bleakley Feb. 25, 1941 2,110,755 Bleakley Mar, 8, 1938 1,676,887 Chamberlin July 10, 1928 2,326,908 Williams Aug. 17, 1943 2,343,793

Paget -.Mar. 7, 1944 are of record in the. 

